PITTSBURGH — The high-occupancy vehicle lanes of Interstate 279 north of Pittsburgh have been closed this morning by a fiery crash that authorities say killed one person. State police continued to examine the scene near the Perrysville Avenue exit in Ross Township. They say the vehicle, believed to be a sport-utility type, was headed north when it hit a concrete wall, and burst into flames after flipping over. Police have yet to release the name of the victim. The accident happened about 2:30 a.m. today, but the HOV lanes remained closed more than four hours later. That was expected to cause traffic delays from the city’s northern suburbs during the morning rush hour. It was not clear when the HOV lanes might reopen. Police were still trying to determine what caused the crash.